People need to seek out new foods because the world has so many mouths to feed. As of 2015， there are more than seven billion people on Earth， according to the United Nations. And by 2100 that number may double. Feeding all of these people means not only improving the way food is grown， but also finding new sources of nutrition.

    And that quest is becoming ever more urgent. If nothing changes， within 35 years， the world's appetite will be greater than the amount of food produced.  That's according to a report released last year.  It was prepared by the Global Harvest Initiative， a private agriculture group based in Washington， D.C.

    Global warming， too， is changing food production.  Scientists predict that rising temperatures will reduce the growth of important crops like wheat， corn and soybeans. Low－ income developing countries will be hit the hardest. When harvests fall， crops become more expensive. And since those foods are also used to feed animals like cows and pigs， meat prices， too， will rise.

    All over the world， researchers are racing against the clock to figure out how best to feed more people in a fast－changing world. And some surprising ideas have begun to come up. Two years ago， scientists introduced the first burger made from meat grown in a lab. The project cost more than $ 300，000， but it's a start. Other researchers are developing seeds that can survive high temperatures and drought.  Still others are finding ways to improve the genes of meat animals so they produce more meat and can stand the heat.

    A gloomy(悲观的) forecast for the planet isn't the only reason to study food's for the future.  It's a creative quest that will inspire people who can think in new ways about existing plants and animals     even insects.  These researchers have used their talents in ways that even they never would have predicted.

a. Increase meat prices，    b. Raise the temperature.

c. Reduce the growth of crops，    d. Lead to the high cost of life.

e. Cause a higher price for crops.